Method of manufacturing integrated circuit configured with two or more single crystal acoustic resonator devices

ABSTRACT

A method of fabricating a configurable single crystal acoustic resonator (SCAR) device integrated circuit. The method includes providing a bulk substrate structure having first and second recessed regions with a support member disposed in between. A thickness of single crystal piezo material is formed overlying the bulk substrate with an exposed backside region configured with the first recessed region and a contact region configured with the second recessed region. A first electrode with a first terminal is formed overlying an upper portion of the piezo material, while a second electrode with a second terminal is formed overlying a lower portion of the piezo material. An acoustic reflector structure and a dielectric layer are formed overlying the resulting bulk structure. The resulting device includes a plurality of single crystal acoustic resonator devices, numbered from (R1) to (RN), where N is an integer greater than 1.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of and claims priority to U.S.application Ser. No. 14/796,939, filed Jul. 10, 2015, which is acontinuation of U.S. application Ser. No. 14/298,100, filed Jun. 6,2014. The present application incorporates by reference, for allpurposes, the following patent applications, all commonly owned: U.S.patent application Ser. No. 14/298,057, filed Jun. 6, 2014 (now U.S.Pat. No. 9,673,384), and U.S. patent application Ser. No. 14/298,076,filed Jun. 6, 2014 (now U.S. Pat. No. 9,537,465).

BACKGROUND OF THE INVENTION

The present invention relates generally to electronic devices. Moreparticularly, the present invention provides techniques related to asingle crystal acoustic resonator. Merely by way of example, theinvention has been applied to a resonator device for a communicationdevice, mobile device, computing device, among others.

Mobile telecommunication devices have been successfully deployedworld-wide. Over a billion mobile devices, including cell phones andsmartphones, were manufactured in a single year and unit volumecontinues to increase year-over-year. With ramp of 4G/LTE in about 2012,and explosion of mobile data traffic, data rich content is driving thegrowth of the smartphone segment—which is expected to reach 2B per annumwithin the next few years. Coexistence of new and legacy standards andthirst for higher data rate requirements is driving RF complexity insmartphones. Unfortunately, limitations exist with conventional RFtechnology that is problematic, and may lead to drawbacks in the future.

From the above, it is seen that techniques for improving electronicdevices are highly desirable.

BRIEF SUMMARY OF THE INVENTION

According to the present invention, techniques generally related toelectronic devices are provided. More particularly, the presentinvention provides techniques related to a single crystal acousticresonator. Merely by way of example, the invention has been applied to aresonator device for a communication device, mobile device, computingdevice, among others.

In an example, the present invention provides a single crystal capacitordielectric material configured on a substrate by a limited area epitaxy.The material is coupled between a pair of electrodes, which areconfigured from a topside and a backside of a substrate member, in anexample. In an example, the single crystal capacitor dielectric materialis provided using a metal-organic chemical vapor deposition, a molecularbeam epitaxy, an atomic layer deposition, a pulsed laser deposition, achemical vapor deposition, or a wafer bonding process. In an example,the limited area epitaxy is lifted-off the substrate and transferred toanother substrate. In an example, the material is characterized by adefect density of less than 1E+11 defects per square centimeter. In anexample, the single crystal capacitor material is selected from at leastone of AN, AlGaN, InN, BN, or other group III nitrides. In an example,the single crystal capacitor material is selected from at least one of asingle crystal oxide including a high K dielectric, ZnO, or MgO.

In an example, a single crystal acoustic electronic device is provided.The device has a substrate having a surface region. The device has afirst electrode material coupled to a portion of the substrate and asingle crystal capacitor dielectric material having a thickness ofgreater than 0.4 microns and overlying an exposed portion of the surfaceregion and coupled to the first electrode material. In an example, thesingle crystal capacitor dielectric material is characterized by adislocation density of less than 10¹² defects/cm². A second electrodematerial is overlying the single crystal capacitor dielectric material.

In an example, the present invention provides a configurable singlecrystal acoustic resonator (SCAR) device integrated circuit. The circuitcomprises a plurality of SCAR devices numbered from 1 through N, where Nis an integer of 2 and greater. Each of the SCAR device has a thicknessof single crystal piezo material formed overlying a surface region of asubstrate member. The single crystal piezo material is characterized bya dislocation density of less than 10¹² defects/cm².

One or more benefits are achieved over pre-existing techniques using theinvention. In particular, the invention enables a cost-effectiveresonator device for communications applications. In a specificembodiment, the present device can be manufactured in a relativelysimple and cost effective manner. Depending upon the embodiment, thepresent apparatus and method can be manufactured using conventionalmaterials and/or methods according to one of ordinary skill in the art.The present device uses a gallium and nitrogen containing material thatis single crystalline. Depending upon the embodiment, one or more ofthese benefits may be achieved. Of course, there can be othervariations, modifications, and alternatives.

A further understanding of the nature and advantages of the inventionmay be realized by reference to the latter portions of the specificationand attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more fully understand the present invention, reference ismade to the accompanying drawings. Understanding that these drawings arenot to be considered limitations in the scope of the invention, thepresently described embodiments and the presently understood best modeof the invention are described with additional detail through use of theaccompanying drawings in which:

FIG. 1 is a simplified diagram illustrating a surface single crystalacoustic resonator according to an example of the present invention.

FIG. 2 is a simplified diagram illustrating a bulk single crystalacoustic resonator according to an example of the present invention.

FIG. 3 is a simplified diagram illustrating a feature of a bulk singlecrystal acoustic resonator according to an example of the presentinvention.

FIG. 4 is a simplified diagram illustrating a piezo structure accordingto an example of the present invention.

FIG. 5 is a simplified diagram illustrating a piezo structure accordingto an alternative example of the present invention.

FIG. 6 is a simplified diagram illustrating a piezo structure accordingto an alternative example of the present invention.

FIG. 7 is a simplified diagram illustrating a piezo structure accordingto an alternative example of the present invention.

FIG. 8 is a simplified diagram illustrating a piezo structure accordingto an alternative example of the present invention.

FIG. 9 is a simplified diagram illustrating a piezo structure accordingto an alternative example of the present invention.

FIG. 10 is a simplified diagram illustrating a piezo structure accordingto an alternative example of the present invention.

FIG. 11 is a simplified diagram of a substrate member according to anexample of the present invention.

FIG. 12 is a simplified diagram of a substrate member according to anexample of the present invention.

FIG. 13 is a simplified table illustrating features of a conventionalfilter compared against the present examples according to examples ofthe present invention.

FIGS. 14-22 illustrate a manufacturing method for a single crystalacoustic resonator device in an example of the present invention.

FIG. 23 illustrates circuit diagrams of the single crystal acousticresonator device in an example of the present invention.

FIGS. 24-32 illustrate a manufacturing method for a single crystalacoustic resonator device in an example of the present invention.

FIG. 33 illustrates circuit diagrams of the single crystal acousticresonator device in an example of the present invention.

FIGS. 34 and 35 illustrate a reflector structure configured on thesingle crystal acoustic resonator device in an example of the presentinvention.

FIG. 36 illustrates circuit diagrams of the integrated reflectorstructure with the single crystal acoustic resonator device of theaforementioned Figures.

FIGS. 37 and 38 illustrate a reflector structure configured on thesingle crystal acoustic resonator device in an example of the presentinvention

FIG. 39 illustrates circuit diagrams of the integrated reflectorstructure with the single crystal acoustic resonator device of theaforementioned Figures.

FIG. 40 illustrates simplified diagrams of a bottom surface region andtop surface region for the single crystal acoustic resonator device inan example of the present invention.

FIGS. 41 and 44 illustrate simplified examples of a single crystalacoustic resonator device configured in a filter ladder network in anexample of the present invention.

FIGS. 45 to 52 illustrate simplified examples of two and three elementsingle crystal acoustic resonator devices according to examples of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

According to the present invention, techniques generally related toelectronic devices are provided. More particularly, the presentinvention provides techniques related to a single crystal acousticresonator. Merely by way of example, the invention has been applied to aresonator device for a communication device, mobile device, computingdevice, among others.

As additional background, the number of bands supported by smartphonesis estimated to grow by 7-fold compared to conventional techniques. As aresult, more bands mean high selectivity filter performance is becominga differentiator in the RF front end of smartphones. Unfortunately,conventional techniques have severe limitations.

That is, conventional filter technology is based upon amorphousmaterials and whose electromechanical coupling efficiency is poor (only7.5% for non-lead containing materials) leading to nearly half thetransmit power dissipated in high selectivity filters. In addition,single crystal acoustic wave devices are expected to deliverimprovements in adjacent channel rejection. Since there are twenty (20)or more filters in present smartphone and the filters are insertedbetween the power amplifier and the antenna solution, then there is anopportunity to improve the RF front end by reducing thermal dissipation,size of power amplifier while enhancing the signal quality of thesmartphone receiver and maximize the spectral efficiency within thesystem.

Utilizing single crystal acoustic wave device (herein after “SAW”device) and filter solutions, one or more of the following benefits maybe achieved: (1) large diameter silicon wafers (up to 200 mm) areexpected to realize cost-effective high performance solutions, (2)electromechanical coupling efficiency is expected to more than triplewith newly engineered strained piezo electric materials, (3) Filterinsertion loss is expected to reduce by 1 dB enabling longer batterylife, improve thermal management with smaller RF footprint and improvingthe signal quality and user experience. These and other benefits can berealized by the present device and method as further provided throughoutthe present specification, and more particularly below.

FIG. 1 is a simplified diagram illustrating a surface single crystalacoustic resonator according to an example of the present invention.This diagram is merely an example, which should not unduly limit thescope of the claims. The present surface single crystal acousticresonator device 100 having a crystalline piezo material 120 overlying asubstrate 110 is illustrated. As shown, an acoustic wave propagates in alateral direction from a first spatial region to a second spatial regionsubstantially parallel to a pair of electrical ports 140, which form aninter-digital transducer configuration 130 with a plurality of metallines 131 that are spatially disposed between the pair of electricalports 140. In an example, the electrical ports on the left side can bedesignated for signal input, while the electrical ports on the rightside are designated for signal output. In an example, a pair ofelectrode regions are configured and routed to a vicinity of a planeparallel to a contact region coupled to the second electrode material.

In a SAW device example, surface acoustic waves produce resonantbehavior over a narrow frequency band near 880 MHz to 915 MHz frequencyband—which is a designated passband for a Europe, Middle East and Africa(EMEA) LTE enabled mobile smartphone. Depending on region of operationfor the communication device, there can be variations. For example, inNorth American transmit bands, the resonator can be designed such thatresonant behavior is near the 777 MHz to 787 MHz frequency passband.Other transmit bands, found in other regions, can be much higher infrequency, such as the Asian transmit band in the 2570 MHz to 2620 MHzpassband. Further, the examples provided here are for transmit bands. Insimilar fashion, the passband on the receiver side of the radio frontend also require similar performing resonant filters. Of course, therecan be variations, modifications, and alternatives.

Other characteristics of surface acoustic wave devices include thefundamental frequency of the SAW device, which is determined by thesurface propagation velocity (determined by the crystalline quality ofthe piezo-electric material selected for the resonator) divided by thewavelength (determined by the fingers in the interdigitated layout inFIG. 1). Measured propagation velocity (also referred to as SAWvelocity) in GaN of approximately 5800 m/s has been recorded, whilesimilar values are expected for AlN. Accordingly, higher SAW velocity ofsuch Group III-nitrides enables a resonator to process higher frequencysignals for a given device geometry.

Resonators made from Group III-nitrides are desirable as such materialsoperate at high power (leveraging their high critical electric field),high temperature (low intrinsic carrier concentration from their largebandgap) and high frequency (high saturated electron velocities). Suchhigh power devices (greater than 10 Watts) are utilized in wirelessinfrastructure and commercial and military radar systems to name a few.Further, stability, survivability and reliability of such devices arecritical for field deployment.

Further details of each of the elements provided in the present devicecan be found throughout the present specification and more particularbelow. In FIGS. 1, 2, and 4-12, the same parts have the same last twodigits with the prefix changed to indicate respective drawings unlessotherwise specified.

FIG. 2 is a simplified diagram illustrating a bulk single crystalacoustic resonator according to an example of the present invention.This diagram is merely an example, which should not unduly limit thescope of the claims. The present bulk single crystal acoustic resonatordevice 200 having a crystalline piezo material is illustrated. As shown,an acoustic wave propagates in a vertical direction from a first spatialregion to a second spatial region between an upper electrode material231 and a substrate member 210. As shown, the crystalline piezo material220 is configured between the upper (231) and lower (232) electrodematerial. The top electrode material 231 is configured underneath aplurality of optional reflector layers, which are formed overlying thetop electrode 231 to form an acoustic reflector region 240.

In a bulk acoustic wave (hereinafter “BAW”) device example, acousticwaves produce resonant behavior over a narrow frequency band near 3600MHz to 3800 MHz frequency band—which is a designated passband for a LTEenabled mobile smartphone. Depending on region of operation for thecommunication device, there can be variations. For example, in NorthAmerican transmit bands, the resonator can be designed such thatresonant behavior is near the 2000 MHz to 2020 MHz frequency passband.Other transmit bands, found in other regions such as the Asian transmitband in the 2500 MHz to 2570 MHz passband. Further, the examplesprovided here are for transmit bands. In similar fashion, the passbandon the receiver side of the radio front end also require similarperforming resonant filters. Of course, there can be variations,modifications, and alternatives.

Other characteristics of single crystal BAW devices include theelectromechanical acoustic coupling in the device, which isproportionate to the piezoelectricity constant (influence by the designand strain of the single crystal piezo layer) divided by the acousticwave velocity (influenced by scattering and reflections in the piezomaterial). Acoustic wave velocity in GaN of over 5300 m/s has beenobserved. Accordingly, high acoustic wave velocity of such GroupIII-nitrides enables a resonator to process higher frequency signals fora given device geometry.

Similar to SAW devices, resonators made from Group III-nitrides aredesirable as such materials operate at high power (leveraging their highcritical electric field), high temperature (low intrinsic carrierconcentration from their large bandgap) and high frequency (highsaturated electron velocities). Such high power devices (greater than 10Watts) are utilized in wireless infrastructure and commercial andmilitary radar systems to name a few. Further, stability, survivabilityand reliability of such devices are critical for field deployment.

Further details of each of the materials provided in the present devicecan be found throughout the present specification and more particularbelow.

In an example, the device has a substrate, which has a surface region.In an example, the substrate can be a thickness of material, acomposite, or other structure. In an example, the substrate can beselected from a dielectric material, a conductive material, asemiconductor material, or any combination of these materials. In anexample, the substrate can also be a polymer member, or the like. In apreferred example, the substrate is selected from a material providedfrom silicon, a gallium arsenide, an aluminum oxide, or others, andtheir combinations.

In an example, the substrate is silicon. The substrate has a surfaceregion, which can be in an off-set or off cut configuration. In anexample, the surface region is configured in an off-set angle rangingfrom 0.5 degree to 1.0 degree. In an example, the substrate is <111>oriented and has high resistivity (greater than 10³ ohm-cm). Of course,there can be other variations, modifications, and alternatives.

In an example, the device has a first electrode material coupled to aportion of the substrate and a single crystal capacitor dielectricmaterial having a thickness of greater than 0.4 microns. In an example,the single crystal capacitor dielectric material has a suitabledislocation density. The dislocation density is less than 10¹²defects/cm², and greater than 10⁴ defects per cm², and variationsthereof. The device has a second electrode material overlying the singlecrystal capacitor dielectric material. Further details of each of thesematerials can be found throughout the present specification and moreparticularly below.

In an example, the single crystal capacitor material is a suitablesingle crystal material having desirable electrical properties. In anexample, the single crystal capacitor material is generally a galliumand nitrogen containing material such as a AlN, AlGaN, or GaN, amongInN, InGaN, BN, or other group III nitrides. In an example, the singlecrystal capacitor material is selected from at least one of a singlecrystal oxide including a high K dielectric, ZnO, MgO, or alloys ofMgZnGaInO. In an example, the high K is characterized by a defectdensity of less than 10¹² defects/cm², and greater than 10⁴ defects percm². Of course, there can be other variations, modifications, andalternatives.

In an example, the single crystal capacitor dielectric material ischaracterized by a surface region at least 50 micron by 50 micron, andvariations. In an example, the surface region can be 200 micron×200 umor as high as 1000 um×1000 um. Of course, there are variations,modifications, and alternatives.

In an example, the single crystal capacitor dielectric material isconfigured in a first strain state to compensate to the substrate. Thatis, the single crystal material is in a compressed or tensile strainstate in relation to the overlying substrate material. In an example,the strained state of a GaN when deposited on silicon is tensilestrained whereas an AlN layer is compressively strain relative to thesilicon substrate.

In a preferred example, the single crystal capacitor dielectric materialis deposited overlying an exposed portion of the substrate. In anexample, the single crystal capacitor dielectric is lattice mismatchedto the crystalline structure of the substrate, and may be straincompensated using a compressively strain piezo nucleation layer such asAlN or SiN.

In an example, the device has the first electrode material is configuredvia a backside of the substrate. In an example, the first electrodematerial is configured via a backside of the substrate. Theconfiguration comprises a via structure configured within a thickness ofthe substrate.

In an example, the electrode materials can be made of a suitablematerial or materials. In an example, each of the first electrodematerial and the second electrode material is selected from a refractorymetal or other precious metals. In an example, each of the firstelectrode material and the second electrode material is selected fromone of tantalum, molybdenum, platinum, titanium, gold, aluminumtungsten, or platinum, combinations thereof, or the like.

In an example, the first electrode material and the single crystalcapacitor dielectric material comprises a first interface regionsubstantially free from an oxide bearing material. In an example, thefirst electrode material and the single crystal capacitor dielectricmaterial comprises a second interface region substantially free from anoxide bearing material. In an example, the device can include a firstcontact coupled to the first electrode material and a second contactcoupled to the second electrode material such that each of the firstcontact and the second contact are configured in a co-planararrangement.

In an example, the device has a reflector region configured to the firstelectrode material. In an example, the device also has a reflectorregion configured to the second electrode material. The reflector regionis made of alternating low impedance (e.g. dielectric) andhigh-impedance (e.g. metal) reflector layers, where each layer istargeted at one quarter-wave in thickness, although there can bevariations.

In an example, the device has a nucleation material provided between thesingle crystal capacitor dielectric material and the first electrodematerial. The nucleation material is typically AlN or SiN.

In an example, the device has a capping material provided between thesingle crystal capacitor dielectric material and the second electrodematerial. In an example, the capping material is GaN.

In an example, the single crystal capacitor dielectric materialpreferably has other properties. That is, the single crystal capacitordielectric material is characterized by a FWHM of less than one degree.

In an example, the single crystal capacitor dielectric is configured topropagate a longitudinal signal at an acoustic velocity of 5000meters/second and greater. In other embodiments where strain isengineered, the signal can be over 6000 m/s and below 12,000 m/s. Ofcourse, there can be variations, modifications, and alternatives.

The device also has desirable resonance behavior when tested using atwo-port network analyzer. The resonance behavior is characterized bytwo resonant frequencies (called series and parallel)—whereby oneexhibits an electrical impedance of infinity and the other exhibits animpedance of zero. In between such frequencies, the device behavesinductively. In an example, the device has s-parameter derived from atwo-port analysis, which can be converted to impedance. From s11parameter, the real and imaginary impedance of the device can beextracted. From s21, the transmission gain of the resonator can becalculated. Using the parallel resonance frequency along the known piezolayer thickness, the acoustic velocity can be calculated for the device.

FIG. 3 is a simplified diagram illustrating a feature of a bulk singlecrystal acoustic resonator according to an example of the presentinvention. This diagram is merely an example, which should not undulylimit the scope of the claims. As shown, diagram 300 shows the presentinvention applied as a band pass filter for RF signals. A specificfrequency range is allowed through the filter, as depicted by thedarkened block elevated from the RF spectrum underneath the wavelengthillustration. This block is matched to the signal allowed through thefilter in the illustration above. Single crystal devices can offerbetter acoustic quality versus BAW devices due to lower filter loss andrelieving the specification requirements on the power amplifier. Thesecan result benefits for devices utilizing the present invention such asextended battery, efficient spectrum use, uninterrupted callerexperience, and others.

FIG. 4 is a simplified diagram illustrating a piezo structure accordingto an example of the present invention. This diagram is merely anexample, which should not unduly limit the scope of the claims. In anexample, the structure 400 is configured on a bulk substrate member 410,including a surface region. In an example, the single crystal piezomaterial epitaxial 420 is formed using a growth process. The growthprocess can include chemical vapor deposition, molecular beam epitaxialgrowth, or other techniques overlying the surface of the substrate. Inan example, the single crystal piezo material can include single crystalgallium nitride (GaN) material, single crystal Al(x)Ga(1-x)N where0<x<1.0 (x=“Al mole fraction”) material, single crystal aluminum nitride(AlN) material, or any of the aforementioned in combination with eachother. Of course, there can also be modifications, alternatives, andvariations. Further details of the substrate can be found throughout thepresent specification, and more particularly below.

FIG. 5 is a simplified diagram illustrating a piezo structure accordingto an alternative example of the present invention. This diagram ismerely an example, which should not unduly limit the scope of theclaims. In an example, the structure 500 is configured overlying anucleation region 530, which is overlying a surface of the substrate510. In an example, the nucleation region 530 is a layer or can bemultiple layers. The nucleation region is made using a piezo-electricmaterial in order to enable acoustic coupling in a resonator circuit. Inan example, the nucleation region is a thin piezo-electric nucleationlayer, which may range from about 0 to 100 nm in thickness, may be usedto initiate growth of single crystal piezo material 520 overlying thesurface of the substrate. In an example, the nucleation region can bemade using a thin SiN or AlN material, but can include variations. In anexample, the single crystal piezo material has a thickness that canrange from 0.2 um to 20 um, although there can be variations. In anexample, the piezo material that has a thickness of about 2 um istypical for 2 GHz acoustic resonator device. Further details of thesubstrate can be found throughout the present specification, and moreparticularly below.

FIG. 6 is a simplified diagram illustrating a piezo structure accordingto an alternative example of the present invention. This diagram ismerely an example, which should not unduly limit the scope of theclaims. In an example, the structure 600 is configured using a GaN piezomaterial 620. In an example, each of the regions are single crystal orsubstantially single crystal. In an example, the structure is providedusing a thin AlN or SiN piezo nucleation region 630, which can be alayer or layers. In an example, the region is unintentional doped (UID)and is provided to strain compensate GaN on the surface region of thesubstrate 610. In an example, the nucleation region has an overlying GaNsingle crystal piezo region (having N_(d)−N_(a): between 10¹⁴/cm³ and10¹⁸/cm³, where N_(d) is concentration of donor atoms and N_(a) is theconcentration of acceptor atoms), and a thickness ranging between 1.0 umand 10 um, although there can be variations. Further details of thesubstrate can be found throughout the present specification, and moreparticularly below.

FIG. 7 is a simplified diagram illustrating a piezo structure accordingto an alternative example of the present invention. This diagram ismerely an example, which should not unduly limit the scope of theclaims. As shown, the structure 700 is configured using an AlN piezomaterial 720. Each of the regions is single-crystal or substantiallysingle crystal. In an example, the structure is provided using a thinAlN or SiN piezo nucleation region 730, which can be a layer or layers.In an example, the region is unintentional doped (UID) and is providedto strain compensate AlN on the surface region of the substrate 710. Inan example, the nucleation region has an overlying AlN single crystalpiezo region (having Nd−Na: between 10¹⁴/cm³ and 10¹⁸/cm³), and athickness ranging between 1.0 um and 10 um, although there can bevariations. Further details of the substrate can be found throughout thepresent specification, and more particularly below.

FIG. 8 is a simplified diagram illustrating a piezo structure accordingto an alternative example of the present invention. This diagram ismerely an example, which should not unduly limit the scope of theclaims. As shown, the structure 800 is configured using an AlGaN piezomaterial 820. Each of the regions is single-crystal or substantiallysingle crystal. In an example, the structure is provided using a thinAlN or SiN piezo nucleation region 830, which can be a layer or layers.In an example, the region is unintentional doped (UID) and is providedto strain compensate AlN on the surface region of the substrate 810. Inan example, the AlGaN single crystal piezo layer 820 is characterized byAl_((x))Ga_((1-x))N and has Al mole composition of 0<x<1.0. Also, thislayer 820 can have a carrier concentration (N_(d)−N_(a), where N_(d) isthe concentration of donor atoms or donor density and N_(a) is theconcentration of acceptor atoms or acceptor density) between 10¹⁴/cm³and 10¹⁸/cm³ and a thickness ranging between 1 um and 10 um, among otherfeatures. Further details of the substrate can be found throughout thepresent specification, and more particularly below.

FIG. 9 is a simplified diagram illustrating a piezo structure accordingto an alternative example of the present invention. This diagram ismerely an example, which should not unduly limit the scope of theclaims. The structure 900 is configured using AlN/AlGaN piezo materials931 and 920. Each of the regions is single-crystal or substantiallysingle crystal. In an example, the structure is provided using a thinAlN or SiN piezo nucleation region 930, which can be a layer or layers.In an example, the region is unintentional doped (UID) and is providedto strain compensate AlN on the surface region of the substrate 910. Inan example, one or more alternating stacks are formed overlying thenucleation region. In an example, the stack includes an AlGaN singlecrystal piezo layer 920 and an AlN single crystal piezo layer 931. In aspecific example, the AlGaN layer 920 can be characterized byAl_((x))Ga_((1-x))N and can have an Al mole composition of 0<x<1.0 and athickness ranging between 1.0 um and 10 um. Also, this layer 920 canhave a carrier concentration (N_(d)−N_(a), where N_(d) is theconcentration of donor atoms or donor density and N_(a) is theconcentration of acceptor atoms or acceptor density) between 10¹⁴/cm³and 10¹⁸/cm³. In a specific example, the AlN layer 931 can have athickness between 1 nm and 30 nm and can be configured to straincompensate the crystal lattice and allow a thicker AlGaN piezo layer920. In an example, the final single crystal piezo layer is AlGaN. In anexample, the structure has a total stack thickness of at least 1 um andless than 10 um, among others. Further details of the substrate can befound throughout the present specification, and more particularly below.

FIG. 10 is a simplified diagram illustrating a piezo structure accordingto an alternative example of the present invention. This diagram ismerely an example, which should not unduly limit the scope of theclaims. As shown, the structure 1000 includes a substrate 1010,piezo-nucleation layer (PNL) 1030, and a piezo layer 1020. The piezolayer 1020 can be a single crystal piezo layer like those describedpreviously. Structure 1000 also has an optional GaN piezo-electric caplayer or layers 1040. In an example, the cap layer 1040 or region can beconfigured on any of the aforementioned examples, among others. In anexample, the cap region can include at least one or more benefits. Suchbenefits include improved electro-acoustic coupling from topside metal(electrode 1) into piezo material, reduced, surface oxidation, improvedmanufacturing, among others. In an example, the GaN cap region has athickness ranging between 1 nm-10 nm, and has a carrier concentration(Nd−Na) between 10¹⁴/cm³ and 10 ¹⁸/cm³, although there can bevariations. Further details of the substrate can be found throughout thepresent specification, and more particularly below.

FIG. 11 is a simplified diagram of a substrate member 1100 according toan example of the present invention. This diagram is merely an example,which should not unduly limit the scope of the claims. In an example,the single crystal acoustic resonator material 1120 can be a singlecrystal piezo material epitaxial grown (using CVD or MBE technique) on asubstrate 1110. The substrate 1110 can be a bulk substrate, a composite,or other member. The bulk substrate 1110 is preferably gallium nitride(GaN), silicon carbide (SiC), silicon (Si), sapphire (Al₂O₃), aluminumnitride (AlN), combinations thereof, and the like.

FIG. 12 is a simplified diagram of a substrate member 1200 according toan example of the present invention. This diagram is merely an example,which should not unduly limit the scope of the claims. In an example,the single crystal acoustic resonator material 1220 can be a singlecrystal piezo material epitaxial grown (using CVD or MBE technique) on asubstrate 1210. The substrate 1210 can be a bulk substrate, a composite,or other member. The bulk substrate 1210 is preferably gallium nitride(GaN), silicon carbide (SiC), silicon (Si), sapphire (Al2O3), aluminumnitride (AlN), combinations thereof, and the like. In an example, thesurface region 1211 of the substrate is bare and exposed crystallinematerial. In this case, surface region 1211 is the starting growthsurface and growth interface.

FIG. 13 is a simplified table illustrating features of a conventionalfilter compared against the present examples according to examples ofthe present invention. As shown, the specifications of the “PresentExample” versus a “Conventional” embodiment are shown with respect tothe criteria under “Filter Solution”.

In an example, the GaN, SiC and Al2O3 orientation is c-axis in order toimprove or even maximize a polarization field in the piezo-electricmaterial. In an example, the silicon substrate orientation is <111>orientation for same or similar reason. In an example, the substrate canbe off-cut or offset. While c-axis or <111> is nominal orientation, anoffcut angle between +/−1.5 degrees may be selected for one or more ofthe following reasons: (1) controllability of process; (2) maximizationof K2 of acoustic resonator, and other reasons. In an example, thesubstrate is grown on a face, such as a growth face. A Ga-face ispreferred growth surface (due to more mature process). In an example,the substrate has a substrate resistivity that is greater than 10⁴ohm-cm, although there can be variations. In an example, the substratethickness ranges 100 um to 1 mm at the time of growth of single crystalpiezo deposition material. Of course, there can be variations,modifications, and alternatives.

As used herein, the terms “first” “second” “third” and “nth” shall beinterpreted under ordinary meaning. Such terms, alone or together, donot necessarily imply order, unless understood that way by one ofordinary skill in the art. Additionally, the terms “top” and “bottom”may not have a meaning in reference to a direction of gravity, whileshould be interpreted under ordinary meaning. These terms shall notunduly limit the scope of the claims herein.

As used herein, the term substrate is associated with Group III-nitridebased materials including GaN, InGaN, AlGaN, or other Group IIIcontaining alloys or compositions that are used as starting materials,or AlN or the like. Such starting materials include polar GaN substrates(i.e., substrate where the largest area surface is nominally an (h k l)plane wherein h=k=0, and l is non-zero), non-polar GaN substrates (i.e.,substrate material where the largest area surface is oriented at anangle ranging from about 80-100 degrees from the polar orientationdescribed above towards an (h k 1) plane wherein 1=0, and at least oneof h and k is non-zero) or semi-polar GaN substrates (i.e., substratematerial where the largest area surface is oriented at an angle rangingfrom about +0.1 to 80 degrees or 110-179.9 degrees from the polarorientation described above towards an (h k l) plane wherein l=0, and atleast one of h and k is non-zero.)

As shown, the present device can be enclosed in a suitable package. Asan example, the packaged device can include any combination of elementsdescribed above, as well as outside of the present specification. Asused herein, the term “substrate” can mean the bulk substrate or caninclude overlying growth structures such as a gallium and nitrogencontaining epitaxial region, or functional regions, combinations, andthe like.

In an example, the present disclosure provides a step-by-stepfabrication of a single-crystal acoustic resonator (SCAR) device.Additionally, the disclosure provides fabrication processes tomanufacture two or more resonators together to provide a SCAR filter,among other devices. In an example, the present processes can beimplemented using conventional high volume wafer fabrication facilitiesfor efficient operations, and competitive costs. Of course, there can beother variations, modifications, and alternatives.

FIGS. 14-22 illustrate a manufacturing method for a single crystalacoustic resonator device in an example of the present invention. Theseillustrations are merely examples, and should not unduly limit the scopeof the claims herein.

Referring to the Figures, an example of a manufacturing process can bebriefly described below:

-   -   1. Start;    -   2. Provide a substrate member, e.g., 150 mm or 200 mm diameter        material, having a surface region;    -   3. Treat the surface region;    -   4. Form an epitaxial material comprising single crystal piezo        material overlying the surface region to a desired thickness;    -   5. Pattern the epitaxial material using a masking and etching        process to form a trench region by causing formation of an        exposed portion of the surface region through a pattern provided        in the epitaxial material;    -   6. Form topside landing pad metal, which may include a stack        that has a metal layer that reacts slowly with etchants in a        backside substrate etching process, as defined below;    -   7. Form topside electrode members, including a first electrode        member overlying a portion of the epitaxial material, and a        second electrode member overlying the topside landing pad metal;    -   8. Mask and remove (via etching) a portion of the substrate from        the backside to form a first trench region exposing a backside        of the epitaxial material overlying the first electrode member,        and a second trench region exposing a backside of the landing        pad metal;    -   9. Form backside resonator metal material for the second        electrode overlying the exposed portion of the epitaxial        material (or piezo membrane) to form a connection from the        epitaxial material to the backside of the landing pad metal        coupled to the second electrode member overlying the topside        landing pad metal;    -   10. Form resonator active area using a masking and etching        process, while electrically and spatially isolating the first        electrode member from the second electrode member on the top        side, while also fine tuning the resonance capacitor;    -   11. Form overlying thickness of protecting dielectric material        (e.g., SiO₂, SiN) overlying an upper surface region on topside        surface; and    -   12. Perform other steps, as desired.

The aforementioned steps are provided for the formation of a resonatordevice using a single crystal capacitor dielectric. As shown, a pair ofelectrode members is configured to provide for contact from one side ofthe device. One of the electrode members uses a backside contact, whichis coupled to a metal stack layer to configure the pair of electrodes.Of course, depending upon the embodiment, steps or a step can be added,removed, combined, reordered, or replaced, or has other variations,alternatives, and modifications. Further details of the presentmanufacturing process can be found throughout the present specification,and more particularly below.

As shown in FIG. 14, the method begins by providing a substrate member1410. The substrate member has a surface region. In an example, thesubstrate member thickness (t) is 400 um, which can have a diameter of150 mm or 200 mm diameter material, although there can be variationsfrom 50 mm to 300 mm. In FIGS. 14 through 22, the same parts have thesame last two digits with the prefix changed to indicate respectivedrawings unless otherwise specified.

In an example, the surface region of the substrate member is treated.The treatment often includes cleaning and/or conditioning. In anexample, the treatment occurs in an MOCVD or LPCVD reactor with ammoniagas flowing at high temperature (e.g. in the range from 940° C. to 1100°C.) at a pressure ranging from one-tenth of an atmosphere to oneatmosphere. Depending upon the embodiment, other treatment processes canalso be used.

In an example, the method includes formation of an epitaxial materialcomprising single crystal piezo material 1420 overlying the surfaceregion to a desired thickness, as shown by device 1400. Using aconfiguration of Trimethylgallium (TMG), Trimethylaluminium (TMA),ammonia (NH₃) and hydrogen (H₂) gases, the epitaxial material is grownunder high temperature in the range of 940° C. to 1100° C. in anatmospheric controlled environment using a MOCVD or LPCVD growthapparatus to a thickness ranging from 0.4 um to 7.0 um, depending ontarget resonance frequency of the capacitor device. The material alsohas a defect density of 10⁴ to 10¹² per cm², although there can bevariations.

In an example, the epitaxial material (1420) is patterned to form afirst-etched epitaxial material 1521 of device 1500 overlying substratemember 1510 (FIG. 15). Patterning involves a masking and etchingprocess. The mask is often 1-3 um of photoresist. Etching useschlorine-based chemistries (gases may include BCl₃, Cl₂, and/or argon)in an RIE or ICP etch tool, under controlled temperature and pressureconditions to adjust the etch rate and sidewall profile. The patterningforms a trench region (or via structure) by causing formation of anexposed portion of the surface region through a pattern provided in thefirst-etched epitaxial material 1521.

In an example, the method forms a topside landing pad metal 1630 ofdevice 1600 (FIG. 16), which may include a stack that has a metal layerthat reacts slowly with etchants in a backside substrate etchingprocess, as defined below. Similar to the previous figure, device 1600includes a substrate member 1610 and a first-etched epitaxial material1621. In an example, the metal is a refractory metal (such as tantalum,molybdenum, tungsten) or other metal (such as gold, aluminum, titaniumor platinum). The metal is used subsequently as a stop region for abackside etching process, as noted.

In an example, the method forms a topside metal structure of device 1700(FIG. 17). Similar to the previous figure, device 1700 includes asubstrate member 1710, a first-etched epitaxial material 1721, and atopside landing pad metal 1730. The topside metal structure has topsideelectrode members, including a first electrode member 1741 overlying aportion of the epitaxial material, and a second electrode member 1742overlying the topside landing pad metal, as shown. The metal structureis made using a refractory metal (such as tantalum, molybdenum,tungsten), and has a thickness of 300 nm, chosen to define the resonantfrequency of the capacitor device.

In an example, the method performs backside processing of device 1800(FIG. 18), by flipping the substrate top-side down. In an example, themethod includes a patterning process of the backside of the substrate.Similar to the previous figure, device 1800 includes a first-etchedepitaxial material 1821, a topside landing pad metal 1830, a firstelectrode member 1841, and a second electrode member 1842. The processuses a mask and removal process via etching a portion of the substrate(1710) from the previous figure to form an etched substrate member 1811.The etching from the backside is used to form a first trench regionexposing a backside of the epitaxial material overlying the firstelectrode member, and a second trench region exposing a backside of thelanding pad metal. In an example, etching is performed usingchlorine-based gas in either an RIE or ICP reactor with temperature andpressure defined to control etch rate, selectivity and sidewall slope.

Next, the method includes formation of a backside resonator metalmaterial 1943 of device 1900 (FIG. 19) for the second electrode member1942 overlying the exposed portion of the epitaxial material (or piezomembrane) 1921 to form a connection from the epitaxial material to thebackside of the landing pad metal coupled to the second electrode member1942 overlying the topside landing pad metal. Similar to the previousfigure, device 1900 also includes an etched substrate member 1911, afirst-etched epitaxial material 1921, a topside landing pad metal 1930,a first electrode member 1941, and a second electrode member 1942.

As shown, the piezo membrane or first-etched epitaxial material 1921 issandwiched between the pair of electrodes, which are configured from thetop-side and backside of the etched substrate member 1911. The member is<111> oriented silicon substrate with a resistivity of greater than 10⁴ohm-cm.

In an example, the method forms or patterns the resonator active area2022 using a masking and etching process of device 2000 (FIG. 20).Similar to the previous figure, device 2000 includes an etched substratemember 2011, a topside landing pad metal 2030, and a backside resonatormetal material 2043. The end objective is to electrically and spatiallyisolate the first electrode member 2041 from the second electrode member2042 on the top side, while also fine tuning the resonance capacitor. Inan example, the resonator active area is 200 um by 200 um. Thepatterning uses chlorine-based RIE or ICP etching technique.

The method forms a thickness of protecting material 2150 of device 2100(FIG. 21). Similar to the previous figure, device 2100 includes anetched substrate member 2111, and active resonator region orsecond-etched epitaxial material 2122, a topside landing pad metal 2130,a first electrode member 2141, a second electrode member 2142, and abackside resonator metal material 2143. In an example, the method formsa combination of silicon dioxide, which forms a conforming structure,and an overlying silicon nitride capping material. The silicon dioxideand silicon nitride materials are formed using a combination of silane,nitrogen and oxygen sources and deposited using a PECVD chamber.

The method forms a first and second electrode (2261, 2262) that areelectrically coupled to the first top electrode 2241 and second topelectrode 2242, respectively, in device 2200 (FIG. 22). Similar to theprevious figure, device 2200 includes an etched substrate member 2211, aresonator active region or second-etched epitaxial material 2222, atopside landing pad metal 2230, a first electrode member 2241, a secondelectrode member 2242, a backside resonator metal material 2243, and aprotecting material 2250. The intrinsic device is marked as 2201. In anexample, the method also may include other steps or other materials, asdesirable.

In an example, the present method can also include one or more of theseprocesses for formation of the upper electrode structures, passivationmaterial, and backside processing. In an example, the present substrateincluding overlying structures can include a surface clean using HCl:H2O(1:1) for a predetermined amount of time, followed by rinse and loadinto sputtering tool.

In the sputtering tool to form the electrode metallization, the methodincludes a molybdenum (Mo) metal (3000 Å) blanket deposition usingsputtering technique on an exposed top side of the single crystal piezomaterial. In an example, if desired, a thin titanium adhesion metal(<100 Å) can be deposited prior to formation of the Mo metal. Suchtitanium metal serves as a glue layer, among other features. In anexample, the method performs a mask and pattern process to etch away Moin field areas (leaving Mo in probe pad, coplanar waveguide (CPW)interconnect, top-plate/first electrode, via landing pad/secondelectrode, and alignment mark areas. In an example, titanium-aluminum(100 Å/4 um) is deposited on Mo metal in probe pad and CPW areas. In anexample, Ti/Al is formed on the landing pad for subsequently depositedcopper-tin metal pillars for wafer-level flip-chip package—CuSn pillarsand die sawing are deposited. In an example, the method forms adielectric passivation (25 um of Spin-on Polymer photo-dielectric(ELECTRA WLP SH32-1-1) of top-side surface, or alternatively acombination of SiN or SiO₂ is formed overlying the top surface.

In an example, the method includes patterning to open bond pads andprobe pads by exposing photo-dielectric and developing away dielectricmaterial on pads. The patterning process completes an upper region ofthe substrate structure, before backside processing is performed.Further details of the present method can be found throughout thepresent specification, and more particularly below.

In an example, the substrate is provided on a flip mount wafer and mount(using photoresist) onto a carrier wafer to begin backside process. Inan example, the backside processing uses a multi-step (e.g., two step)process. In an example, the wafer is thinned from about 500 um to about300 um and less using backside grinding process, which may also includepolishing, and cleaning. In an example, the backside is coated withmasking material, such as photoresist, and patterned to open trenchregions for the piezo material and the landing pad regions. In anexample, the method includes a shallow etch process into the substrate,which can be silicon for example. In an example, the method coats thebackside with photoresist to open and expose a backside region of thepiezo material, which exposes a full membrane area, which includesenclosed the piezo material and the landing pad areas. In an example,the method also performs an etch until the piezo material and thelanding pads are exposed. In an example, the “rib” support is featurewhich results from 2-step process, although there can be variations, asfurther described below.

In an example, the backside is patterned with photoresist to align thebackside pad metal (electrode #2), interconnect and landing pad. In anexample, the backside is treated using a cleaning process using diluteHCl:H2O (1:1), among other suitable processes. In an example, the methodalso includes deposition of about 3000 A of Mo metal in selective areas,provided that the backside of the wafer is patterned with metal in aselective manner and not blanket deposition. In an example, the metal isformed to reduce parasitic capacitance and enables routing of backsidefor circuit implementation, which is beneficial for different circuitnode interconnections. In an example, if desired, a thin titaniumadhesion metal (<100 Å) can be deposited prior to Mo as a glue material.

In an example, the method also includes formation of a dielectricpassivation (25 um of spin-on polymer photo-dielectric (e.g., ELECTRAWLP SH32-1-1) of backside side surface for mechanical stability. In anexample in an alternative example, the method includes deposition of SiNand/or SiO₂ to fill the backside trench region to provide suitableprotection, isolation, and provide other features, if desired.

In an example, the method then separates and/or unmounts the completedsubstrate for transfer into a wafer carrier. The completed substrate hasthe devices, and overlying protection materials. In an example, thesubstrate is now ready for saw and break, and other backend processessuch as wafer level packaging, or other techniques. Of course, there canbe other variations, modifications, and alternatives.

FIG. 23 illustrates circuit diagrams of the single crystal acousticresonator device in an example of the present invention. Thisillustration is merely an example, and should not unduly limit the scopeof the claims herein. Circuit 2301 shows a block diagram with the piezomembrane 2322 sandwiched between the first top electrode 2361 and thesecond top electrode 2362. The connection area 2303 of block diagram2301 is represented in the circuit diagram 2302, showing an equivalentcircuit configuration.

FIGS. 24-32 illustrate a manufacturing method for a single crystalacoustic resonator device in an example of the present invention. Thisillustration is merely an example, and should not unduly limit the scopeof the claims herein.

An example of an alternative manufacturing process can be brieflydescribed below:

-   -   1. Start;    -   2. Provide a substrate member, e.g., 150 mm or 200 mm diameter        material, having a surface region;    -   3. Treat the surface region to prepare for epitaxial growth;    -   4. Form an epitaxial material comprising single crystal piezo        material overlying the surface region to a desired thickness;    -   5. Pattern the epitaxial material using a masking and etching        process to form a trench region by causing formation of an        exposed portion of the surface region through a pattern provided        in the epitaxial material; alternatively, the patterning of the        epitaxial material may also occur using a laser drill technique;    -   6. Form topside landing pad metal, which may include a stack        that has a metal layer that reacts slowly with etchants in a        backside substrate etching process, as defined below;    -   7. Form topside electrode members, including a first electrode        member overlying a portion of the epitaxial material, and a        second electrode member overlying the topside landing pad metal;    -   8. Mask and remove (via etching) a portion of the substrate from        the backside to form a single trench region exposing a backside        of the epitaxial material overlying the first electrode member,        and exposing a backside of the landing pad metal; a shallow        “rib” structure may be formed using a two-step mask and etch        process with the goal of providing mechanical support to the        epitaxial material;    -   9. Form backside resonator metal material for the second        electrode overlying the exposed portion of the epitaxial        material (or piezo membrane) to form a connection from the        epitaxial material to the backside of the landing pad metal        coupled to the second electrode member overlying the topside        landing pad metal;    -   10. Form resonator active area with low surface leakage current        using a passivation process, which electrically and spatially        isolates the first electrode member from the second electrode        member on the top side, while also fine tuning the resonance        capacitor; a dielectric passivation layer (such as SiN or SiO₂)        is deposited using PECVD technique using silane gas in a        controlled temperature and pressure environment to control        dielectric index of refraction;    -   11. Form overlying thickness of protecting dielectric material        (options include SiO₂, SiN, or spin-on polymer coating)        overlying an upper surface region on topside surface; and    -   12. Perform other steps, as desired.

The aforementioned steps are provided for the formation of a resonatordevice using a single crystal capacitor dielectric. As shown, a pair ofelectrode members is configured to provide for contact from one side ofthe device. One of the electrode members uses a backside contact, whichis coupled to a metal stack layer to configure the pair of electrodes.Of course, depending upon the embodiment, steps or a step can be added,removed, combined, reordered, or replaced, or has other variations,alternatives, and modifications. Further details of the presentmanufacturing process can be found throughout the present specification,and more particularly below.

As shown in FIG. 24, the method begins by providing a substrate member2410. The substrate member has a surface region. In an example, thesubstrate member thickness is 400 um, which can have a diameter of 150mm or 200 mm diameter material, although there can be variations from 50mm to 300 mm. In FIGS. 24 through 32, the same parts have the same lasttwo digits with the prefix changed to indicate respective drawingsunless otherwise specified.

In an example, the surface region of the substrate member is treated.The treatment often includes cleaning and/or conditioning. In anexample, the treatment occurs in an MOCVD or LPCVD reactor with ammoniagas flowing at high temperature (e.g. in the range from 940° C. to 1100°C.) at a pressure ranging from one-tenth of an atmosphere to oneatmosphere.

In an example, the method includes formation of an epitaxial materialcomprising single crystal piezo material 2420 overlying the surfaceregion to a desired thickness (t), as shown by device 2400. Using aconfiguration of Trimethylgallium (TMG), Trimethylaluminium (TMA),ammonia (NH₃) and hydrogen (H₂) gases, the epitaxial material is grownunder high temperature in the range of 940° C. to 1100° C. in anatmospheric controlled environment using a MOCVD or LPCVD growthapparatus to a thickness ranging from 0.4 um to 7.0 um, depending ontarget resonance frequency of the capacitor device. The material alsohas a defect density of 10⁴ to 10¹² per cm².

In an example, the epitaxial material (2420) is patterned to form anetched epitaxial material 2521 of device 2500 overlying substrate member2510 (FIG. 25). Patterning involves a masking and etching process. Themask is often 1-3 um of photoresist. Etching uses chlorine-basedchemistries (gases may include BCl₃, Cl₂, and/or argon) in an RIE or ICPetch tool, under controlled temperature and pressure conditions toadjust the etch rate and sidewall profile. The patterning forms a trenchregion (or via structure) by causing formation of an exposed portion ofthe surface region through a pattern provided in the etched epitaxialmaterial 2521.

In an example, the method forms a topside landing pad metal 2630 ofdevice 2600 (FIG. 26), which may include a stack that has a metal layerthat reacts slowly with etchants in a backside substrate etchingprocess, as defined below. Similar to the previous figure, device 2600includes a substrate member 2610 and an etched epitaxial material 2621.In an example, the metal is a refractory metal (such as tantalum,molybdenum, tungsten) or other metal (such as gold, aluminum, titaniumor platinum). The metal is used subsequently as a stop region for abackside etching process, as noted.

In an example, the method forms a topside metal structure of device 2700(FIG. 27). Similar to the previous figure, device 2700 includessubstrate member 2710, an etched epitaxial material 2721, and a topsidelanding pad metal 2730. The topside metal structure has topsideelectrode members, including a first electrode member 2741 overlying aportion of the epitaxial material, and a second electrode member 2742overlying the topside landing pad metal, as shown. The metal structureis made using a refractory metal (such as tantalum, molybdenum,tungsten), and has a thickness of 300 nm, chosen to define the resonantfrequency of the capacitor device.

In an example, the method performs backside processing of device 2800(FIG. 28), by flipping the substrate top-side down. In an example, themethod includes a patterning process of the backside of the substrate.Similar to the previous figure, device 2800 includes an etched epitaxialmaterial 2821, a topside landing pad metal 2830, a first electrodemember 2841, and a second electrode member 2842. The process uses a maskand removal process via etching a portion of the substrate (2710) fromthe previous figure to form an etched substrate member 2811. The etchingfrom the backside is used to form a first trench region exposing abackside of the epitaxial material overlying the first electrode member,and a second trench region exposing a backside of the landing pad metal.A support member 2812 can be configured between the two trench regions.In an example, the support member can be recessed from a bottom sidesurface region, although there can be variations. In an example, etchingis performed using chlorine-based gas in either an RIE or ICP reactorwith temperature and pressure defined to control etch rate, selectivityand sidewall slope.

Next, the method includes formation of a backside resonator metalmaterial 2943 of device 2900 (FIG. 29) for the second electrode member2921 overlying the exposed portion of the epitaxial material (or piezomembrane) 2921 to form a connection from the epitaxial material to thebackside of the landing pad metal coupled to the second electrode member2942 overlying the topside landing pad metal. Similar to the previousfigure, device 2900 also includes an etched substrate member 2911, asupport member 2912, an etched epitaxial material 2921, a topsidelanding pad metal 2930, a first electrode member 2941, and a secondelectrode member 2942.

As shown, the piezo membrane or etched epitaxial material 2921 issandwiched between the pair of electrodes, which are configured from thetop-side and backside of the substrate member. The member is <111>oriented silicon substrate with a resistivity of greater than 10⁴ohm-cm.

In an example, the resonator active area is 200 um by 200 um. Thepatterning uses chlorine-based RIE or ICP etching technique. Similar tothe previous figure, device 3000 of FIG. 30 includes an etched substratemember 3011, a support member 3012, an etched epitaxial material 3021, atopside landing pad metal 3030, and a backside resonator material 3043,a first electrode member 3041, and a second electrode member 3042.

The method forms a passivation layer 3050 of device 3000 (FIG. 30) and athickness of protecting material 3170 of device 3100 (FIG. 31). Similarto the device of FIG. 30, device 3100 includes an etched substratemember 3111, a support member 3112, an etched epitaxial material 3121, atopside landing pad metal 3130, a backside resonator material 3143, afirst electrode member 3141, a second electrode member 3142, and apassivation layer 3150. In an example, the method forms a combination ofsilicon dioxide, which forms a conforming structure, and an overlyingsilicon nitride capping material. The silicon dioxide and siliconnitride materials are formed using a combination of silane, nitrogen andoxygen sources and deposited using a PECVD chamber.

The method forms a first and second electrode terminals (3261, 3262)that are electrically coupled to the first top electrode 3241 and secondtop electrode 3242, respectively, in device 3200 (FIG. 32). Similar tothe previous figure, device 3200 includes an etched substrate member3211, a support member 3212, an etched epitaxial material 3221, atopside landing pad metal 3230, a backside resonator material 3243, afirst electrode member 3241, a second electrode member 3242, apassivation layer 3250, and a protecting material 3270. The intrinsicdevice is marked as 3201. In an example, the method also may includeother steps or other materials, as desirable.

In an example, the present method can also include one or more of theseprocesses for formation of the upper electrode structures, passivationmaterial, and backside processing. In an example, the present substrateincluding overlying structures can include a surface clean using HCl:H2O(1:1) for a predetermined amount of time, followed by rinse and loadinto sputtering tool.

In the sputtering tool to form the electrode metallization, the methodincludes a molybdenum (Mo) metal (3000 Å) blanket deposition usingsputtering technique on an exposed top side of the single crystal piezomaterial. In an example, if desired, a thin titanium adhesion metal(<100 Å) can be deposited prior to formation of the Mo metal. Suchtitanium metal serves as a glue layer, among other features. In anexample, the method performs a mask and pattern process to etch away Moin field areas (leaving Mo in probe pad, coplanar waveguide (CPW)interconnect, top-plate/first electrode, via landing pad/secondelectrode, and alignment mark areas. In an example, titanium-aluminum(100 Å/4 um) is deposited on Mo metal in probe pad and CPW areas. In anexample, Ti/Al is formed on the landing pad for subsequently depositedcopper-tin metal pillars for wafer-level flip-chip package—CuSn pillarsand die sawing are deposited. In an example, the method forms adielectric passivation (25 um of Spin-on Polymer photo-dielectric(ELECTRA WLP SH32-1-1) of top-side surface, or alternatively acombination of SiN or SiO₂ is formed overlying the top surface.

In an example, the method includes patterning to open bond pads andprobe pads by exposing photo-dielectric and developing away dielectricmaterial on pads. The patterning process completes an upper region ofthe substrate structure, before backside processing is performed.Further details of the present method can be found throughout thepresent specification, and more particularly below.

In an example, the substrate is provided on a flip mount wafer and mount(using photoresist) onto a carrier wafer to begin backside process. Inan example, the backside processing uses a multi-step (e.g., two step)process. In an example, the wafer is thinned from about 500 um to about300 um and less using backside grinding process, which may also includepolishing, and cleaning. In an example, the backside is coated withmasking material, such as photoresist, and patterned to open trenchregions for the piezo material and the landing pad regions. In anexample, the method includes a shallow etch process into the substrate,which can be silicon for example. In an example, the method coats thebackside with photoresist to open and expose a backside region of thepiezo material, which exposes a full membrane area, which includesenclosed the piezo material and the landing pad areas. In an example,the method also performs an etch until the piezo material and thelanding pads are exposed. In an example, the “rib” support is featurewhich results from 2-step process, although there can be variations.

In an example, the backside is patterned with photoresist to align thebackside pad metal (electrode #2), interconnect and landing pad. In anexample, the backside is treated using a cleaning process using diluteHCl:H2O (1:1), among other suitable processes. In an example, the methodalso includes deposition of about 3000 A of Mo metal in selective areas,provided that the backside of the wafer is patterned with metal in aselective manner and not blanket deposition. In an example, the metal isformed to reduce parasitic capacitance and enables routing of backsidefor circuit implementation, which is beneficial for different circuitnode interconnections. In an example, if desired, a thin titaniumadhesion metal (<100 Å) can be deposited prior to Mo as a glue material.

In an example, the method also includes formation of a dielectricpassivation (25 um of spin-on polymer photo-dielectric (e.g., ELECTRAWLP SH32-1-1) of backside side surface for mechanical stability. In anexample in an alternative example, the method includes deposition of SiNand/or SiO₂ to fill the backside trench region to provide suitableprotection, isolation, and provide other features, if desired.

In an example, the method then separates and/or unmounts the completedsubstrate for transfer into a wafer carrier. The completed substrate hasthe devices, and overlying protection materials. In an example, thesubstrate is now ready for saw and break, and other backend processessuch as wafer level packaging, or other techniques. Of course, there canbe other variations, modifications, and alternatives.

FIG. 33 illustrates circuit diagrams of the single crystal acousticresonator device in an example of the present invention. Thisillustration is merely an example, and should not unduly limit the scopeof the claims herein. Circuit 3301 shows a block diagram with the piezomembrane 3322 sandwiched between the first top electrode 3361 and thesecond top electrode 3362. The connection area 3303 of block diagram3301 is represented in the circuit diagram 3302, showing an equivalentcircuit configuration.

In an example, the present disclosure illustrations an acousticreflector structure which can be added, only if needed, or desirable. Inan example, the acoustic reflector on a single crystal acousticresonator device (SCAR) device can provide improved acoustic coupling,so called K². In conventional BAW devices, an acoustic resonator isinserted into substrate/carrier material, which may be cumbersome andnot efficient, although used. In an example, because a portion of thesubstrate is removed from backside of single crystal piezo material fromthe device, then the acoustic reflector is likely not needed or desiredon either side of the acoustic resonator. However, in contrast toconventional bulk acoustic wave devices where reflector is integratedinto the substrate, the acoustic reflector is integrated on the topsideof the device where is can serve two functions: (i) reduce moisturesensitivity to SCAR device, AND (ii) provide acoustic isolation fromfilter device and surrounding environment (similar to a Faraday cage),among other functions. These and other features can be found throughoutthe present specification and more particularly below.

FIGS. 34 and 35 illustrate a reflector structure configured on thesingle crystal acoustic resonator device (3400, 3500) in an example ofthe present invention. As shown, the devices have similar features asone of the prior examples (FIGS. 14-22). Device 3400 includes an etchedsubstrate member 3410, a second-etched epitaxial material 3422, atopside landing pad metal 3430, a first electrode member 3441, a secondelectrode member 3442, and a backside resonator material 3443. Device3500 includes an etched substrate member 3510, a second-etched epitaxialmaterial 3522, a topside landing pad metal 3530, a first electrodemember 3541, a second electrode member 3542, and a backside resonatormaterial 3543. Additionally, the device is configured with a reflectorstructure including alternating quarter-wave layers of high acousticimpedance 3452, 3552 (e.g. metals such as Mo, W, Cu, Ta) and lowimpedance materials 3451, 3551 (e.g., dielectrics such as to formacoustic reflector above acoustic resonator device). FIG. 35 also showsa first electrode terminal 3561 horizontally coupled to the first topelectrode 3541 and a second electrode terminal 3562 vertically coupledto the second top electrode 3542. The intrinsic device is marked as3501. Of course, there can be other variations, modifications, andalternatives.

FIG. 36 illustrates circuit diagrams of the integrated reflectorstructure with the single crystal acoustic resonator device of theaforementioned Figures. This illustration is merely an example, andshould not unduly limit the scope of the claims herein. As shown,circuit 3601 is a block diagram with the piezo membrane 3622 sandwichedbetween the first top electrode 3661 and the second top electrode 3662.The connection area 3603 of block diagram 3601 is represented in thecircuit diagram 3602, showing an equivalent circuit configuration.

In an example, the present invention can provide an acoustic resonatordevice comprising a bulk substrate member, having a surface region, anda thickness of material. In an example, the bulk substrate has a firstrecessed region and a second recessed region, and a support memberdisposed between the first recessed region and the second recessedregion.

In an example, the device has a thickness of single crystal piezomaterial formed overlying the surface region. In an example, thethickness of single crystal piezo material has an exposed backsideregion configured with the first recessed region and a contact regionconfigured with the second recessed region. The device has a firstelectrode member formed overlying an upper portion of the thickness ofsingle crystal piezo material and a second electrode member formedoverlying a lower portion of the thickness of single crystal piezomaterial to sandwich the thickness of single crystal piezo material withthe first electrode member and the second electrode member. In anexample, the second electrode member extends from the lower portion thatincludes the exposed backside region to the contact region. In anexample, the device has a second electrode structure configured with thecontact region and a first electrode structure configured with the firstelectrode member.

As shown, the device also has a dielectric material overlying an uppersurface region of a resulting structure overlying the bulk substratemember. The device has an acoustic reflector structure configuredoverlying the first electrode member, the upper portion, the lowerportion, and the second electrode member. As shown, the acousticreflector structure has a plurality of quarter wave layers configuredspatially within the dielectric material.

FIGS. 37 and 38 illustrate a reflector structure configured on thesingle crystal acoustic resonator device (3700, 3800) in an example ofthe present invention. This illustration is merely an example, andshould not unduly limit the scope of the claims herein. As shown, thedevice has similar features as one of the prior examples (FIGS. 24-32).Device 3700 includes an etched substrate member 3711, a support member3712, an etched epitaxial material 3721, a topside landing pad metal3730, a first electrode member 3741, a second electrode member 3742, anda backside resonator material 3743. Device 3800 includes an etchedsubstrate member 3811, a support member 3812, an etched epitaxialmaterial 3821, a topside landing pad metal 3830, a first electrodemember 3841, a second electrode member 3842, and a backside resonatormaterial 3843. Additionally, the device is configured with a reflectorstructure including alternating quarter-wave layers of high acousticimpedance 3752, 3852 (e.g. metals such as Mo, W, Cu, Ta) and lowimpedance materials 3751, 3752 (e.g., dielectrics such as to formacoustic reflector above acoustic resonator device). FIG. 38 also showsa first electrode terminal 3861 horizontally coupled to the first topelectrode 3841 and a second electrode terminal 3862 vertically coupledto the second top electrode 3842. The intrinsic device is marked as3801. Of course, there can be other variations, modifications, andalternatives.

FIG. 39 illustrates circuit diagrams of the integrated reflectorstructure with the single crystal acoustic resonator device of theaforementioned Figures. This illustration is merely an example, andshould not unduly limit the scope of the claims herein. As shown,circuit 3901 is a block diagram with the piezo membrane 3922 sandwichedbetween the first top electrode 3961 and the second top electrode 3962.The connection area 3903 of block diagram 3901 is represented in thecircuit diagram 3902, showing an equivalent circuit configuration.

In an example, the present invention can provide an acoustic resonatordevice comprising a bulk substrate member, having a surface region, anda thickness of material. In an example, the bulk substrate has a firstrecessed region and a second recessed region, and a support memberdisposed between the first recessed region and the second recessedregion.

In an example, the device has a thickness of single crystal piezomaterial formed overlying the surface region. In an example, thethickness of single crystal piezo material has an exposed backsideregion configured with the first recessed region and a contact regionconfigured with the second recessed region. The device has a firstelectrode member formed overlying an upper portion of the thickness ofsingle crystal piezo material and a second electrode member formedoverlying a lower portion of the thickness of single crystal piezomaterial to sandwich the thickness of single crystal piezo material withthe first electrode member and the second electrode member. In anexample, the second electrode member extends from the lower portion thatincludes the exposed backside region to the contact region. In anexample, the device has a second electrode structure configured with thecontact region and a first electrode structure configured with the firstelectrode member.

As shown, the device also has a dielectric material overlying an uppersurface region of a resulting structure overlying the bulk substratemember. The device has an acoustic reflector structure configuredoverlying the first electrode member, the upper portion, the lowerportion, and the second electrode member. As shown, the acousticreflector structure has a plurality of quarter wave layers configuredspatially within the dielectric material.

FIG. 40 illustrates simplified diagrams of a bottom surface region andtop surface region for the single crystal acoustic resonator device inan example of the present invention. As shown, FIG. 40 includes a topview 4001 and bottom view 4003, each with a correspondingcross-sectional view 4002 and 4004, respectively. These views show aresonator device similar to those described previously. A piezo membrane4020 is disposed overlying a substrate 4010. The top side of the deviceincludes a first and second top electrode 4041, 4042. The etchedunderside of the substrate includes a bottom electrode 4043. Of course,there can be variations, modifications, and alternatives.

FIGS. 41 and 44 illustrate simplified examples of a single crystalacoustic resonator device configured in a filter ladder network in anexample of the present invention. This illustration is merely anexample, and should not unduly limit the scope of the claims herein. Inexamples, the following description provides illustrations andfabrication processes for manufacturing two-or-more resonators togetherto produce a SCAR filter, among other elements.

Referring to FIG. 41, the method begins by taking physicalimplementation for SCAR device 4100 (details found in FIG. 22) andtranslating into circuit element 4102, as shown. The circuit elementincludes a first electrode 4161, a second electrode 4162, and aresonance circuit device 4101 in between the two electrodes. Also,device 4100 includes an etched substrate member 4111, an second-etchedepitaxial material 4122, a topside landing pad metal 4130, a firstelectrode member 4141, a second electrode member 4142, a backsideresonator material 3743, a first electrode terminal 4161, and a secondelectrode terminal 4162. In an example, each of the acoustic resonatordevices comprises a bulk substrate structure, having a surface region,and a thickness of material. In an example, the bulk substrate structurehas a first recessed region and a second recessed region, and a supportmember disposed between the first recessed region and the secondrecessed region. Of course, there can be variations.

In an example, the device has a thickness of single crystal piezomaterial formed overlying the surface region. In an example thethickness of single crystal piezo material has an exposed backsideregion configured with the first recessed region and a contact regionconfigured with the second recessed region. In an example, the singlecrystal piezo material has a thickness of greater than 0.4 microns,although there can be variations. In an example, the single crystalpiezo material is characterized by a dislocation density of less than10¹² defects/cm², while there can be variations.

In an example, the device has a first electrode member formed overlyingan upper portion of the thickness of single crystal piezo material and asecond electrode member formed overlying a lower portion of thethickness of single crystal piezo material to sandwich the thickness ofsingle crystal piezo material with the first electrode member and thesecond electrode member, the second electrode member extending from thelower portion that includes the exposed backside region to the contactregion. In an example, a second electrode terminal is electricallycoupled to the contact region and a first electrode terminal iselectrically coupled to the first electrode member. In an example, thedevice has a dielectric material overlying an upper surface region of aresulting structure overlying the bulk substrate member and an acousticreflector structure configured overlying the first electrode member, theupper portion, the lower portion, and the second electrode member.

Alternatively, the device can include any of the other aforementionedfeatures, and others. Of course there can be other variations,modifications, and alternatives. Further details of the present examplescan be found throughout the present specification and more particularlybelow.

Referring to FIG. 42, a series shunt configuration 4200 of circuitelements R1, R2, R3, R4, R5, R6, and R7 are shown, although there can bevariations and modifications. That is, the configuration can include agreater quantity of resonators or fewer, depending upon the example. Asshown, the illustration configures a filter ladder network used in anacoustic filter that is made up of series-shunt configure SCARs.

Referring now to FIG. 43, the monolithic filter ladder network has aplurality of single crystal acoustic resonator devices numbered from R1,R2, R3, R4, R5, R6, and R7 are configured on a common substrate member.Circuit diagram 4300 corresponds to the device configuration 4301. Ofcourse, there can be a greater quantity or fewer devices that have beenconfigured together.

In an example, each of the acoustic resonator device comprises a bulksubstrate structure, having a surface region, and a thickness ofmaterial. In an example, the bulk substrate structure has a firstrecessed region and a second recessed region, and a support memberdisposed between the first recessed region and the second recessedregion. Of course, there can be variations.

In an example, the device has a thickness of single crystal piezomaterial formed overlying the surface region. In an example thethickness of single crystal piezo material has an exposed backsideregion configured with the first recessed region and a contact regionconfigured with the second recessed region. In an example, the singlecrystal piezo material has a thickness of greater than 0.4 microns,although there can be variations. In an example, the single crystalpiezo material is characterized by a dislocation density of less than10¹² defects/cm², while there can be variations.

In an example, the device has a first electrode member formed overlyingan upper portion of the thickness of single crystal piezo material and asecond electrode member formed overlying a lower portion of thethickness of single crystal piezo material to sandwich the thickness ofsingle crystal piezo material with the first electrode member and thesecond electrode member, the second electrode member extending from thelower portion that includes the exposed backside region to the contactregion. In an example, a first electrode terminal is electricallycoupled to the first electrode member and a second electrode structureis electrically coupled to the contact region and the second electrodemember. In an example, the device has a dielectric material overlying anupper surface region of a resulting structure overlying the bulksubstrate member and an acoustic reflector structure configuredoverlying the first electrode member, the upper portion, the lowerportion, and the second electrode member. Alternatively, the device caninclude any of the other aforementioned features, and others.

As shown, R1, R3, R5, and R7 are configured in a serial manner such thatthe second electrode terminal of R1 is coupled to the first electrodeterminal of R3 and the second electrode terminal of R3 is coupled to thefirst electrode terminal of R5 and the second electrode terminal of R5is coupled to the first electrode terminal of R7. The circuit furthercomprises a first node configured between the second electrode terminalof R2 and the first electrode terminal of R3, a second node isconfigured between the second electrode terminal of R3 and the firstelectrode terminal of R5, and a third node is configured between thesecond electrode terminal of R5 and the first electrode terminal of R7.

In an example, R2 is configured between the first node and a lowercommon node such that the first electrode terminal of R2 is connected tothe first node and the second electrode terminal of R2 is connected tothe lower common node. In an example, R4 is configured between thesecond node and the lower common node such that the first electrodeterminal is connected to the second node and the second electrodeterminal is connected to the lower common node. In an example, R6 isconfigured between the third node and the lower common node such thatthe first electrode terminal of R6 is connected to the third node andthe second electrode terminal of R6 is connected to the lower commonnode.

In an example, given the single device has both electrodes on the topsurface (or a common side) due to the use of a backside via (frombackside electrode 2 to topside electrode 2), the present circuit iswired accordingly with each SCAR device having a backside via as shownin top right. In an example, seven backside vias are included that mayconsume greater portions of the substrate structures. Further examplesof the present circuit devices can be found throughout the presentspecification and more particularly below.

Referring to FIG. 44, the following illustration configures a filterwith reduced or even minimal use of vias to save substrate area. Circuitdiagram 4400 corresponds to the device configuration 4401. In anexample, the range of values for the present filter configuration isfrom seven down to one, or a single via (shown right). In an example,the present illustration uses the following boundary conditions: (1)Input of R1 and output of R7 are arranged such they are both topsidenode 1, (2) maximize the number of internal nodes, which use commonnode, and (3) the common node (bottom of R2, R4, R6) combine at the topsurface of the substrate. As shown, only a single via is included, whichleads to savings in expense, processing, and substrate area. Of course,there are multiple examples that can range from the single via to sevenvias or more.

In an example, the present invention provides a configurable monolithicladder network with a plurality of single crystal acoustic resonator(SCAR) devices. These devices are numbered from R1 to R7 and areconfigured on a common substrate member. Each of these devices issimilar to the SCAR devices described previously and each includes afirst electrode terminal and a second electrode terminal. The firstelectrode terminals of devices R1 and R7 are electrically coupled to afirst common top node. The second electrode terminals of devices R1, R2,and R3 are electrically coupled to a first common internal node. Thefirst electrode terminals of devices R3, R4, and R5 are electricallycoupled to a second common top node. The second electrode terminals ofdevices R5, R6, and R7 are electrically coupled to a second commoninternal node. The first electrode terminals of devices R2 and R6 andthe second electrode terminal of device R4 are electrically coupled to alower common node. In an example, the second electrodes are shared on acommon internal node using a backside connection and metallization. Inan example, the first electrodes are shared using a top side connection,which couple each of them together. In an example, only R4 has a viastructure, which couples to the lower common node. Of course, there canbe variations, modifications, and alternatives. In an example, the fewervias leads to less parasitic capacitance or other loads, and reducesprocesses, and improves substrate usage, which are beneficial for themanufacture of highly integrated devices.

FIGS. 45 to 52 illustrate simplified examples of two and three elementsingle crystal acoustic resonator devices according to examples of thepresent invention. This illustration is merely an example, and shouldnot unduly limit the scope of the claims herein. In examples, thefollowing description provides illustrations for two- or three-elementSCAR devices, which are useful at the circuit level to implement afilter. In an example, some devices do not include a via structure,which is beneficial and more efficient.

Referring to FIG. 45, the illustration shows a filter ladder structure4500 discussed earlier, which can be configured from two elementdevices, R1, R2, R3, R4, R5, R6, and R7 in an example. As shown, R1 andR2 can be configured to form a series shunt two-element device 4501 inan example. As shown, R6 and R7 can be configured to form a series shunttwo-element device 4502 in an example. Of course, there can be othervariations.

Referring to FIG. 46, the illustration shows the same filter ladderstructure 4600 discussed earlier can be constructed three element “Y”and “Pi” devices in an example. In an example, R1, R2 and R3 can beconfigured to make up a series-shunt-series “Y” element SCAR device4601. In an example, R4, R5 and R6 can be configured to make up ashunt-series-shunt three-element “Pi” SCAR device 4602. In an example,other three element “Y” and “Pi” SCAR devices can be constructed fromthis network, e.g., R5-R6-R7 make up a “Y” device, R2-R3-R4 make up a“Pi” device. Of course, there can be other alternatives, modifications,and variations. In an example, which refers to FIG. 47, the illustrationcan provide a lowest count of vias in a SCAR filter or any desirablecount, depending upon the embodiment. FIG. 47 can show a similarconfiguration (4700/4701) to that shown in FIG. 44 (4400/4401). Furtherdetails of the present examples, can be found throughout the presentspecification and more particularly below.

In an example, the description illustrates a series-shunt two-elementthree-terminal SCAR device by FIG. 48. In an example, R1 & R2, amongother combinations, as noted can be configured from two simple SCARstructures. In an example, such two-element device 4801 has no vias, andtwo terminals including T1, T2, which are on a top side of the substratemember and a third-terminal (T3) is on backside of the substrate. In anexample, the description illustrates the shunt-series two-element threeterminal SCAR device 4800. In an example, referencing R1-R2 fromleft-to-right, a series-shunt device is illustrated. From right-to-leftto left, a shunt-series device is illustrated and has the same physicalstructure as the aforementioned device. Of course, there can be othervariations, modifications, and alternatives.

Referring now to FIG. 49, the description illustrates a “Y”three-terminal SCAR device without via structure, which reduces the sizeof the device. As shown and has been described, R1, R2, and R3, amongother combinations, form a three-element three terminal “Y” configuredSCAR device 4900 in an example. Such example has notable feature, suchas no via structures, T1, T2, T3 are connections configured on thetopside of the substrate member for bonding wires. In an example, thedevice also has node two (2), which is common for R1, R2, and R3, andconfigured “internally” and connected on the backside of the substratemember. In an example, the device is a series shunt seriesconfiguration, and has three separate SCAR regions corresponding tothree devices to make up the “Y” configuration device.

Referring now to FIG. 50, the description illustrates a “Y”three-terminal SCAR device with a single via structure, which reducesthe size of the device. As shown and has been described, R3, R4, and R5,among other combinations, form a three-element three terminal “Y”configured SCAR device 5000 in an example. Such example has notablefeatures, such as a single via on a backside connected to a front-sideor topside of the substrate member. In an example, the device also hasT1 and T2 contacts configured to and accessible to the backside of thesubstrate. T3 is configured to and accessible to the front-side of thesubstrate. The node one (1), which is common for R3, R4, and R5, isconfigured “internally” and is connected on the frontside of thesubstrate member. In an example, the device is a series shunt seriesconfiguration, and has three separate SCAR regions corresponding tothree devices to make up the “Y” configuration device.

Referring to FIG. 51, the description illustrates a “Pi”, three-terminalSCAR device with a single via structure in an example. As shown in theillustration, R2, R3, and R4, among other combinations, form athree-element, three terminal “Pi” configured SCAR device 5100. Suchdevice has notable features such as a single backside via structure toroute a backside connect to a front-side of the substrate. In anexample, node two (2) for each of the devices R2 and R3 are connected toone another on the backside and form terminal 1 (T1). In an example,terminal 3, which is T3, is a contact that is accessible to thefront-side of substrate. In an example, nodes one (1) 1 for each deviceR3 and R4 are configured to and connected on the front-side and formterminal 2 (T2). In an example, the device is a shunt series shuntconfiguration. In an example, the device includes three separate SCARregions for corresponding to the three devices to form three (3)elements which form and make-up the “Pi” configuration. As shown is asimplified illustration of a shunt series shunt three (3)-element, threeterminal “Pi” SCAR device having a single via structure on the R4 shuntleg or member. Of course, there can be variations, alternatives, andmodifications.

Referring to FIG. 52, the description illustrates a “Pi”, three-terminalSCAR device with two (2) backside via structures in an example. Asshown, the device has been mentioned in an earlier example, however, thepresent device has an additional via on terminal 1 (T1) configured thecontact region from backside to front-side in this example. In anexample, the device has notable features, such as two (2) backside viastructures to route the backside contact region to connect to thefront-side of the substrate. In an example, the device has node two (2)for each device elements R2 and R3 that are connected to one another onthe backside and then routed to front-side of the substrate using viastructure to form terminal 1 (T1). In an example, terminal 3 (T3) isconfigured to a contact region accessible to the front-side ofsubstrate. In an example, the node 1 (1) for each device elements R3 andR4 are configured to and connected on the front-side and form terminal 2(T2). In an example, the device provides a shunt series shuntconfiguration. Additionally, the device includes use of three separateSCAR regions related to the devices, which form and make-up “Pi”configuration. In an example, as shown, is the shunt series shunt threeelement, three terminal “Pi” SCAR device 5200 having a single via on theR4 shunt leg plus a single via structure 1 connecting internal node two(2) for R2 and R3 to configured and make the T1 connection to thefront-side of the substrate.

While the above is a full description of the specific embodiments,various modifications, alternative constructions and equivalents may beused. Therefore, the above description and illustrations should not betaken as limiting the scope of the present invention which is defined bythe appended claims.

What is claimed is:
 1. A method for fabricating a monolithic filterladder network, the monolithic filter ladder network comprising aplurality of single crystal acoustic resonator devices, numbered from R1to RN, where N is an integer greater than 1, configured on a commonsubstrate member, the method comprising: providing a bulk substratestructure, having a surface region, and a thickness of material, thebulk substrate structure having a first recessed region and a secondrecessed region, and a support member disposed between the firstrecessed region and the second recessed region, the bulk substratestructure being made of a material that is one of a gallium nitride(GaN), silicon carbide (SiC), silicon (Si), sapphire (Al₂O₃), oraluminum nitride (AlN); forming a thickness of single crystal piezomaterial overlying the surface region, the thickness of single crystalpiezo material having an exposed backside region configured with thefirst recessed region and a contact region configured with the secondrecessed region, the single crystal piezo material having a thickness ofgreater than 0.4 microns, the single crystal piezo material beingcharacterized by a dislocation density of less than 10¹² defects/cm²;forming a first electrode member overlying an upper portion of thethickness of single crystal piezo material; forming a second electrodemember overlying a lower portion of the thickness of single crystalpiezo material to sandwich the thickness of single crystal piezomaterial with the first electrode member and the second electrodemember, the second electrode member extending from the lower portionthat includes the exposed backside region to the contact region; forminga first electrode terminal electrically coupled with the first electrodemember; forming a second electrode terminal electrically coupled to thesecond electrode member at the contact region; forming a dielectricmaterial overlying at least the first and second electrode members andthe surface region of the bulk substrate structure; and forming anacoustic reflector structure configured overlying the first electrodemember, the upper portion, the lower portion, and the second electrodemember.
 2. The method of claim 1 wherein the support member isconfigured in a plane coincident with a bottom surface region of thebulk substrate structure.
 3. The method of claim 1 wherein the supportmember is configured in a plane off-set and recessed in reference to abottom surface region of the bulk substrate structure, but protruding inreference to the first and second recessed regions.
 4. The method ofclaim 1 wherein the single crystal piezo material being characterized byX-ray diffraction with clear peak at a detector angle (2-Theta)associated with single crystal film and whose Full Width Half Maximum(FWHM) is measured to be less than 1.0°.
 5. The method of claim 1wherein N is equal to at least 7, and R1, R3, R5 and R7 are configuredin a serial manner such that the second electrode terminal of R1 iscoupled to the first electrode terminal of R3 and the second electrodeterminal of R3 is coupled to the first electrode terminal of R5 and thesecond electrode terminal of R5 is coupled to the first electrodeterminal of R7; and further comprising a first node configured betweenthe second electrode structure terminal of R1 and the first electrodeterminal of R3; a second node is configured between the second electrodeterminal of R3 and the first electrode structure terminal of R5; and athird node is configured between the second electrode terminal of R5 andthe first electrode terminal of R7.
 6. The method of claim 1 wherein Nis equal to at least 7, and R1, R3, R5, and R7 are configured in aserial manner such that the second electrode terminal of R1 is coupledto the first electrode terminal of R3 and the second electrode terminalof R3 is coupled to the first electrode terminal of R5 and the secondelectrode terminal of R5 is coupled to the first electrode terminal ofR7; and further comprising a first node configured between the secondelectrode terminal of R1 and the first electrode terminal of R3; asecond node is configured between the second electrode terminal of R3and the first electrode terminal of R5; and a third node is configuredbetween the second electrode terminal of R5 and the first electrodeterminal of R7; and wherein R2 is configured between the first node anda lower common electrode; R4 is configured between the second node andthe lower common electrode; and R6 is configured between the third nodeand the lower common electrode.
 7. The method of claim 1 wherein N isequal to at least 7 and R1, R3, R5, and R7 are configured in a serialmanner such that the second electrode terminal of R1 is coupled to thefirst electrode terminal of R3 and the second electrode terminal of R3is coupled to the first electrode terminal of R5 and the secondelectrode terminal of R5 is coupled to the first electrode terminal ofR7; and further comprising a first node configured between the secondelectrode terminal of R1 and the first electrode terminal of R3; asecond node is configured between the second electrode terminal of R3and the first electrode terminal of R5; and a third node is configuredbetween the second electrode terminal of R5 and the first electrodeterminal of R7; and wherein R2 is configured between the first node anda lower common electrode such that the first electrode terminal of R2 isconnected to the first node and the second electrode terminal of R2 isconnected to the lower common electrode; R4 is configured between thesecond node and the lower common electrode such that the first electrodeterminal is connected to the second node and the second electrodeterminal is connected to the lower common electrode; and R6 isconfigured between the third node and the lower common electrode suchthat the first electrode terminal of R6 is connected to the third nodeand the second electrode terminal of R6 is connected to the lower commonelectrode.
 8. The method of claim 1 wherein N is equal to at least 7 andR1, R2, and R3 are configured to share a first common node; wherein R3,R4, and R5 are configured to share a second common node; wherein R5, R6,and R7 are configured to share a third common node; and wherein R2, R4,and R6 are configured to share a fourth common node.
 9. The method ofclaim 1 wherein at least one of the plurality of acoustic resonatordevices including R1, R2, R3, R4, R5, R6, or R7 comprises a viastructure electrically coupled to the contact region.
 10. The method ofclaim 1 wherein N is equal to at least 7 and R1, R2, and R3 areconfigured to share a first common node; wherein R3, R4, and R5 areconfigured to share a second common node; wherein R5, R6, and R7 areconfigured to share a third common node; and wherein R2, R4, and R6 areconfigured to share a fourth common node; and R4 is configured with avia structure coupled to the fourth common node.
 11. The method of claim1 wherein the thickness of single crystal piezo material selected fromat least one of AlN, AlGaN, InN, BN, or other group III nitrides. 12.The method of claim 1, wherein the thickness of single crystal piezomaterial is a single crystal oxide selected from at least one of a highK dielectric, ZnO, or MgO; wherein the high K is characterized by thedislocation density of less than 10¹² defects/cm² and greater than 10⁴defects/cm².
 13. The method of claim 1 wherein the each of the firstelectrode terminal and the second electrode terminal is selected fromone of tantalum or molybdenum.
 14. A method of fabricating aconfigurable monolithic filter ladder network comprising a plurality ofsingle crystal acoustic resonator (SCAR) devices, numbered from R1 toRN, where N is an integer greater than 1, configured on a commonsubstrate member, the method comprising: forming a bulk substratestructure, having a surface region, and a thickness of material, thebulk substrate structure having a first recessed region and a secondrecessed region, the bulk substrate structure being made of a materialthat is one of a gallium nitride (GaN), silicon carbide (SiC), silicon(Si), sapphire (Al₂O₃), or aluminum nitride (AlN), and a support memberdisposed between the first recessed region and the second recessedregion; forming a thickness of single crystal piezo material overlyingthe surface region, the thickness of single crystal piezo materialhaving an exposed backside region configured with the first recessedregion and a contact region configured with the second recessed region,the single crystal piezo material having a thickness of greater than 0.4microns, the single crystal piezo material being characterized by adislocation density of less than 10¹² defects/cm²; forming a firstelectrode member overlying an upper portion of the thickness of singlecrystal piezo material; forming a second electrode member overlying alower portion of the thickness of single crystal piezo material tosandwich the thickness of single crystal piezo material with the firstelectrode member and the second electrode member, the second electrodemember extending from the lower portion that includes the exposedbackside region to the contact region; and forming a first electrodeterminal electrically coupled with the first electrode member; forming asecond electrode terminal electrically coupled to the second electrodemember at the contact region; forming a dielectric material overlying atleast the first and second electrode members and the surface region ofthe bulk substrate structure.
 15. The method of claim 14 wherein N isequal to at least 7; wherein R1 and R2 are configured to form a seriesshunt first two-element device; and R6 and R7 are configured to form aseries shunt second two-element device.
 16. The method of claim 14wherein N is equal to at least 7; and wherein (R1), (R2) and (R3) areconfigured to make up a first series-shunt-series Y element SCAR device;and (R4), (R5) and (R6) are configured to make up a shunt-series-shuntthree-element Pi SCAR device.
 17. The method of claim 14 wherein thethickness of single crystal piezo material selected from at least one ofAlN, AlGaN, InN, BN, or other group III nitrides.
 18. The method ofclaim 14, wherein the thickness of single crystal piezo material is asingle crystal oxide selected from at least one of a high K dielectric,ZnO, or MgO; wherein the high K is characterized by the dislocationdensity of less than 10¹² defects/cm² and greater than 10⁴ defects/cm².19. The method of claim 14 wherein the each of the first electrodeterminal and the second electrode terminal is selected from one oftantalum or molybdenum.